Risks from heat, animal disease and erosion to impact New Zealand agriculture as climate changes

Scientists from Manaaki Whenua—Landcare Research worked closely with researchers from NIWA, AgResearch and Plant & Food Research to model the likely risks of climate change across New Zealand’s agricultural sectors. The study is published in Journal of the Royal Society of New Zealand .

The results – which generally indicate that current crop ranges are shifting southwards and that animal health problems are increasing and also shifting southwards – are available as downloadable geographic information systems (GIS) layers from the Whitiwhiti Ora Data Supermarket.

To create the maps, a suite of models of varying complexity was developed to identify threats and opportunities for arable, horticultural, and pastoral land uses. The models combined general assessments of climatic hazard events, such as heat stress and extreme rainfall, with the vulnerability of specific crops and farming systems to these hazards.

Four different scenarios for future greenhouse gas emissions were developed, including a worst-case scenario assuming an increase in average global temperatures of as much as 4°C by 2100.

The modeling results, which are immediately available in Data Supermarket, include the following likely changes:

• Heat stress could become a bigger problem for the agricultural sector, especially in areas where wheat is grown, although rising temperatures and reduced frosts could create new opportunities for crops such as onions, peas and potatoes in some areas.
• Grape varieties that grow in cooler climates may be moved south, but grape ripening periods in different parts of the country will shorten, which could complicate harvest schedules.
• Pasture productivity may increase, but intestinal parasites and facial eczema in livestock could spread further in a warmer environment, even under the most cautious climate change scenario.
• As storms become more frequent and intense, particularly in the soft, mountainous terrain of New Zealand, mass movement and soil erosion are expected to increase.

“The new maps are a huge step forward in understanding and showing the impacts of climate change on New Zealand’s primary sector,” says Dr Linda Lilburne, a researcher at Manaaki Whenua, “but there are still many questions to be answered, particularly around the timing of threats or opportunities in the future.

“For example, will droughts become more frequent or longer, or will increased pasture production mean that farms high in the mountains will be better placed to fatten lambs?”

To answer these questions, the researchers suggest that work is now needed with farming systems scientists and agricultural experts to develop detailed interpretations of the effects of climate change for a range of different farm types, locations and commercial interests. This research will also help the agricultural sector plan for future adaptation and develop resilience to climate change.